A fang is a long, pointed tooth. In mammals, a fang is a canine tooth, used for biting and tearing flesh. In snakes, it is a venom-injecting tooth (see snake venom). Spiders also have fangs, which are part of the chelicerae. Some fantasy creatures such as dragons have fangs.

Fangs are most common in carnivores or omnivores, but some herbivores, such as fruit bats, carry them as well. They are generally used to hold or swiftly kill prey, such as in large cats. Omnivorous animals, such as bears, use their fangs when hunting fish or other prey, but they are not needed for consuming fruit. Apes also have fangs, which they use for threats and fighting. However, the relatively short canines on humans are not considered to be fangs.